Vehicle steering brake and clutch control

ABSTRACT

A crawler tractor vehicle having steering clutches and associated steering brake includes a control apparatus for each clutch and brake system, including a valve made up of a valve body, and a clutch valving spool and a brake valving spool movably associated therewith. In one embodiment, the clutch valving spool and brake valving spool are identical in configuration, and are disposed in a common bore. Actuator means are associated with such clutch valving spool and brake valving spool, in one embodiment including an actuator assembly made up of a plurality of plungers movable relative to each other and relative to the valve body to provide particular movement of the clutch and brake valving spools. In another embodiment, the actuator means comprise mechanical linkage means, for providing movement of brake and clutch valving spools positioned in respective separate bores defined by the valve body.

This is a division, of Ser. No. 688,798, filed May 21, 1976 now U.S.Pat. No. 4,093,048.

BACKGROUND OF THE INVENTION

This invention relates to steering to tractors and more particularly, tothe steering of tractors which include steering clutches and steeringbrakes.

In track-type tractors steering is accomplished by interrupting thedrive to the drive wheel or sprocket on one side or the other of thetractor, and may be assisted by applying a brake selectively to the oneor other of the drive components. Examples of such systems are disclosedin U.S. Pat. No. 3,895,703, and U.S. Pat. No. 3,899,058, both assignedto the assignee of this invention. Further of interest are U.S. Pat. No.2,433,443, U.S. Pat. No. 3,376,846, and British Pat. No. 1,218,526, eachof which disclose a system of the above generally described type. Whilesuch systems have been found relatively effective for the particularenvironmental structures with which they are to be combined, it is to beunderstood that it is always highly desirable to further increase theoperating efficiency of such a system to provide particular results,meanwhile insuring that such a system is simple, relatively inexpensive,reliable, and highly efficient. Particular attention should be paid tothe ease of construction of such a system, combined with the overallsimplicity thereof. Additionally, attention should be paid to providingthe operator of the vehicle information of the status of the system andits effect on the vehicle during the continuing actuation process of asystem. That is, for example, it is deemed highly desirable that theoperator of such a system be aware of the fact that he is in atransition stage between one drive state of the vehicle and another, orthat he is approaching such a drive transition stage. While certain ofthe above systems attempt to deal with such problems, it will beunderstood that particular structure which provides the operator withproper and accurate information as to the state thereof is highlydesirable.

Of more general interest in this area is U.S. Pat. No. 2,989,986(assigned to the assignee of this invention), which discloses ahydraulic control valve for actuating steering clutches.

SUMMARY OF THE INVENTION

It is accordingly an object of this invention to provide, in a vehiclehaving steering clutches and associated steering brakes, control meanswhich sequentially effect disengagement of a steering clutch and thenactuation of an associated steering brake.

It is a further object of this invention to provide, in a vehicle havingsteering clutches and steering brakes, a control system which, whilefulfilling the above object, is extremely simple in design and efficientin use.

It is a still further object of this invention to provide, in a vehiclehaving steering clutches and steering brakes, a system which provides afeedback of information to the operator of the vehicle so that suchoperator can determine the state of such control system.

Broadly stated, the invention is in a vehicle in which driving force isapplied to both sides thereof, including clutch and brake systemsassociated respectively with both sides thereof and responsive to fluidpressure from a source thereof, for steering of the vehicle. Each clutchand brake system is associated with a side of the vehicle, and comprisesclutch means disengageable to disconnect the driving force applied tothat side of the vehicle and engageable to connect the driving force tothat side of the vehicle, and brake actuatable to brake that side of thevehicle and releasable to release that side of the vehicle. Theinvention comprises a control apparatus for each clutch and brake systemcomprising a valve comprising a valve body defining a bore, and firstand second valving spools movably disposed within and along said bore.The invention further comprises first means for providing fluidcommunication between the source and the valve body bore, and secondmeans for providing fluid communication between the valve body bore andthe clutch means. Further included are third means for providing fluidcommunication between the valve body bore and the brake means, andfourth means for providing fluid communication from the valve body boreand through which fluid pressure may be released from the valve bodybore. The first valving spool is movable within the bore to first andsecond positions relative to the valve body, the first valving spool inone of the first and second positions allowing release of fluid pressurefrom the clutch means through the second means for providing fluidcommunication and the fourth means for providing fluid communication.The first valving spool in the other of the first and second positionsprovides communication of fluid pressure from the source through thefirst means for providing fluid communication, through the second meansfor providing fluid communication, to the clutch means. The secondvalving spool is movable within the bore to first and second positionsrelative to the valve body, the second valving spool in one of the firstand second positions providing communication of fluid pressure from thesource through the first means for providing fluid communication,through the third means for providing fluid communication, to the brakemeans, the second valving spool in the other of the first and secondpositions allowing release of fluid pressure from the brake meansthrough the third means for providing fluid communication, and thefourth means for providing fluid communication. Further included areactuator means operatively coupled with the first and second valvingspools so that movement of the actuator means in one direction providesmovement of the first and second valving spools to their respectivefirst positions, and movement of the actuator means in another directionprovides movement of the first and second valving spools in theirrespective second positions.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will become apparent from astudy of the following specification and drawings, in which:

FIG. 1 is a schematic view of a first embodiment of a control system asapplied to a vehicle;

FIG. 2 is a sectional plan elevation of the control valve means of thesystem of FIG. 1;

FIG. 3 is a sectional view taken along the line III--III of FIG. 2;

FIG. 4 is an enlarged view of the actuator plunger means of FIG. 3;

FIG. 5 is an enlarged view of the clutch spool area of the control valveof FIG. 3;

FIG. 6 is an enlarged view of the area of the brake spool of FIG. 3;

FIG. 7 is a sectional elevation of a portion of the apparatus of FIG. 1for independently operating the brakes of the vehicle;

FIG. 8 is a sectional elevation of a portion of the system of FIG. 1 foractuating the brakes of the vehicle in a vehicle parking situation;

FIG. 9 is a sectional view of a portion of the actuator means for movingthe plunger means of the apparatus;

FIG. 10 is a graphical illustration of various parameters of the systemof FIGS. 1-9 illustrating the operation thereof;

FIG. 11 is a view similar to that shown in FIG. 3, but of an alternativeembodiment of control valve shown therein;

FIG. 12 is a view of an enlarged portion of the plunger means of FIG.11;

FIG. 13 is a view similar to that shown in FIG. 1, but of an alternateembodiment of overall systems;

FIG. 14 is a view similar to that shown in FIG. 2, but of yet anotheralternate embodiment of control valve; and

FIG. 15 is a view taken along the line XV--XV of FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Shown in FIG. 1 is an overall system 20 for actuating the steeringclutches and brakes of a vehicle (not shown). The engine of the vehicledrives through a multi-speed transmission 22 and through gears 24 todrive axle portions 26,28. The axle portions 26,28 includes respectiveclutches 30,32 of the type which are engaged upon release of fluidpressure therefrom, and released upon application of fluid pressurethereto. Engagement of clutch 30 provides that power is transmittedtherethrough to drive sprocket 34 on one side of the vehicle, andengagement of clutch 32 provides that power is transmitted therethroughto drive sprocket 36, on the other side of the vehicle. The powerapplied to the sprockets 34, 36 acts, of course, as driving force forthe vehicle, propelling along crawler tracks indicated by broken lines.

The sprocket 34 also has associated therewith a brake 38 which is of thetype which is applied upon release of fluid pressure therefrom, andreleased upon application of fluid pressure thereto. Application of suchbrake 38 retards movement of the sprocket 34, and release of such brake38 allows the sprocket 34 to rotate freely upon power applied theretothrough the clutch 30. The sprocket 36 also has a brake 40 associatedtherewith, which is also engaged upon release of fluid pressure theretoand released upon application of fluid pressure thereto. Such brake 40of course operates in a manner similar to the brake 38 previouslydescribed, but in association with the sprocket 36. A transmissionselector control 42 is included in the system, for providing thatappropriate transmission speeds, i.e., first, second, and third speeds,and appropriate directions, i.e., forward and reverse, can be selected.

A fluid pump 44 is included in the system, to supply pressurized fluidto a control valve 46 through conduits 48,50,52. Such control valve 46is shown in detail in FIGS. 2 and 3. As shown therein, the control valve46 includes a control valve portion 54 for controlling the clutch andbrake system 56 including clutch 30 and brake 38, and a control valveportion 58 for controlling the clutch and brake system 60 includingclutch and brake 32, 40. As such control valve portions 54,58 areidentical in structure and operation, only the control valve portion 54will be described in detail.

The control valve portion 54 is made up of a valve body 62 made up of amain body portion 64 and end plates 66,68 fixed thereto and defining anelongated bore 70. Disposed within the bore 70 adjacent one end thereofis a first valving spool 72 (FIGS. 3 and 5), which is movable along andwithin the bore 70. The valving spool 72 is made up of a main valvingspool portion 74 and an end portion 76 secured thereto by means of asnap ring 78 disposed in a groove defined by the main portion 74. Aresilient helical spring 82 is disposed between the end plate 66 andvalving spool 72 as shown. A slug 84 is disposed in a bore 86 defined bythe spool 72, and is positioned to bear against the end plate 66. Thebore 86 communicates with an inner spool chamber 88, and positioned inthe inner spool chamber 88 is a valve poppet 90 defining a passage 92therethrough. The valve poppet 90 is seatable against a seat portion 94defined by the valving spool 72 therewithin, and such poppet 90 isbiased into a seating position by a resilient spring 96 within thechamber 88. The valving spool 72 defines an annular recessed portion 98between the ends thereof, and radial ports 100 communicate the recessedportion 98 with the chamber 88. The opposite end of the valving spoolhas associated therewith a slug 102 which defines a radial lip 104 whichseats on the end of such valving spool 72.

At the opposite end of the bore, and positioned movably therewithin andtherealong, is another or second valving spool 106 (FIGS. 3 and 6). Thevalving spool 106 is made up of a main valving spool portion 108 and anend portion 110 secured thereto by means of a snap ring 112 disposed ina groove defined by the main portion 108. A resilient helical spring 114is disposed between the end plate and valving spool 106 as shown. A slug116 is disposed in a bore 118 defined by the spool 106, and ispositioned to bear against the end plate 68. The bore 118 communicateswith an inner spool chamber 120, and positioned in the inner spoolchamber 120 is a valve poppet 122 defining a passage 124 therethrough.The valve poppet 122 is seatable against a seat portion 126 defined bythe valving spool 106 therewithin, and such poppet 122 is biased into aseating position by a resilient spring 128 within the chamber 120. Thevalving spool 106 defines an annular recessed portion 130 between theends thereof, and radial ports 132 communicate the recessed portion 130with the chamber 120.

It is to be noted that the valving spools 72,106 are identical inconfiguration, with end 134 of valving spool 72 being substantiallyidentical to corresponding end 136 of valving spool 106, and end 138 ofvalving spool 72 being substantially identical to corresponding end 140of valving spool 106. The valving spools 72,106 are positioned so thatthe end 134 is most adjacent the end 136. That is, the valving spool 106is positionally reversed relative to the valving spool 72 for movableassociation with the valve body 62.

Referring to FIGS. 1, 2 and 3, it is to be seen that the conduits 50,52are actually branch conduits for providing fluid communication betweenthe source 142 and the valve body bore 70. A conduit 144 provides fluidcommunication between the valve body bore 70 and the clutch 30. Yetanother conduit 146 provides fluid communication between the valve bodybore 70 and the brake 38. Fluid pressure may be released from the valvebody bore 70 through the conduit 148, which communicates the valve bodybore 70 with tank 142. The branch conduit 50 which supplies pressure tothe bore 70 is associated with a priority valve 150 the operation ofwhich will be described in detail.

The valve body 62 defines an inner chamber 152 filled with fluid, whichis also communicated to tank 142 through conduit 149, communicating withthe conduit 148. Such inner chamber 152 communicates through passages154,156 (FIG. 2) with yet another area of the bore 70, adjacent thevalving spool 72.

It will be seen that the valving spool 72 is movable within the bore 70to a first position, i.e., rightward in FIG. 3, relative to the valvebody 62 to allow release of fluid pressure from the clutch 30 throughthe conduit 144 and through the passages 156,154, chamber 152, andconduits 149,148. The valving spool 72 is movable to a second positionrelative to the valve body 62, i.e., leftward in FIG. 3, for providingfluid communication of fluid pressure by means of the pump 44 associatedwith the source 142, through the conduits 48,50, and through the conduit144 to the clutch 30, to disengage the clutch 30.

It will further be seen that the valving spool 106 is movable to a firstposition relative to the valve body 62, i.e., rightward relativethereto, to provide communication of fluid pressure from the pump 44through the conduits 48,52 and through the conduit 146 to the brake 38,to release the brake 38. The valving spool 106 is movable to a secondposition, i.e., leftward relative to the valve body 62 as shown in FIG.3, to release fluid pressure from the brake 38 through the conduit 146and through the conduit 148, to apply the brake 38.

Disposed within the chamber 152 defined by the valve body 62 areactuator means 158 operatively coupled with the valving spools 72,106.The actuator means 158 comprise an actuator assembly 160 (FIGS. 3 and 4)positioned generally between the valving spools 72,106, and alignedtherewith along the bore 70. The actuator assembly 160 includes aplunger assembly 162 including an outer first plunger 164 defining anannular groove 166 thereabout. A yoke 168 is pivotally mounted to thevalve body 62 by means of a transverse pin 170 (FIG. 9), and the arms172,174 of the yoke 168 extend upwardly to either side of the plunger164. A pin 176 is secured to the arm 174, and is disposed in the groove166 on one side of the plunger 164, and a pin 178 is likewise secured tothe arm 172 and extends inward of the groove 166 on the other side ofthe plunger 164. Pivotally secured to the outer end of the pin 178 is ashaft 180 defining a radial flange 182, and a cable 184 is threadablysecured to the shaft 180 and extends outwardly of the valve body 62. Aresilient helical spring 186 is disposed between a portion of the valvebody 62 and the flange 182, to urge the shaft 180 and cable 184relatively rightwardly as shown in FIG. 2. It will be seen that movementof the cable 184 leftwardly in FIG. 2 pivots the yoke 168 to move theplunger 164 leftwardly against the resilience of the spring 186.

The cable 184 is associated with a hand control 188 through well-knownmeans, and of course a like cable is associated with the other valvecontrol portion 58 for association with the brake 40 and clutch 32, tobe mechanically interconnected with another hand control 190 in awell-known manner.

It will be seen that movement of the hand control 188 in one directionmoves the plunger 164 leftwardly (FIG. 3), and movement of the handcontrol 188 in the other direction moves the plunger 164 rightwardly,the plunger 164 actually being movable along the bore 70 defined by thevalve body 62.

A second plunger 192 (FIGS. 3 and 4) is positioned adjacent the plunger164, and is movable relative thereto within a bore 194 defined by theplunger 164, and also along the bore 70 defined by the valve body 62. Aresilient helical spring 196 interconnects the radial lip 104 defined bythe slug 102 associated with the valving spool 72, and a face 198defined by the plunger 192. A resilient helical spring 200 interconnectsa face 202 defined by the plunger 164 and a face 204 defined by theplunger 192 to urge them relatively apart. The plunger 164 defines aguide member 206 which is actually a separate member secured to theplunger 164 by means of a snap ring 208, and disposed on an O-ring 210.The guide member 206 is disposed through a bore 212 in a third plunger214, with the third plunger 214 being movable along the guide member 206for guiding movement of the third plunger 214 relative to the plunger164. The guide member 206 and plunger 214 are disposed through a bore216 defined by the second plunger 192 and movable therewithin andrelative thereto. The helical spring 82 (FIGS. 2 and 3) urges thevalving spool 72 toward the plunger 164, and the helical spring 114urges the valving spool 106 toward the plunger 164. A helical spring 218interconnects the plunger 214 and plunger 164 to urge them relativelyapart. Retaining means in the form of a snap ring 220 (FIG. 4) issecured to the end of the guide member 206 for limiting movement of theplunger 214 and plunger 192 relative to the plunger 164 under the urgingof the resilient means 200,218.

The plunger 164 defines a bore 222 (FIGS. 3 and 4) which communicateswith a chamber 224, and a slug 226 is reciprocably disposed within thebore 222. Upon pressurization of the chamber 224 in a manner to bedescribed, the slug 226 is moved rightwardly (FIG. 3) to bear againstthe end of a piston spring capsule rod 228. The spring capsule rod 228makes up part of a spring capsule 231 which consists of guide 232,helical spring 242, sleeve or cylinder 240, rod 228 and snap ring 230.The rod 228 passes through an opening in guide 232, such guide 232 beingreciprocably disposed within a bore 234 defined by the plunger 164, andpressurization of such chamber 224 moves the slug 226 rightwardly tomove the rod 228 rightwardly to bring the guide 232 into engagement witha snap ring 236 (FIGS. 3 and 4) secured to the plunger 164 within thebore 234. The piston head 238 (FIG. 3) on piston rod 228 is reciprocablymounted in the cylinder 240, which bears against the valving spool 106.The helical spring 242 is disposed about the piston and cylinderassembly 228,238,240, and urges the plunger 164 and valving spool 106relatively part.

Through such means described, it will be seen that the rod 223 isoperatively coupled with the plunger 164 and the cylinder 240 isoperatively coupled with the valving spool 106.

As stated above, means will be described further on by which pressure isapplied to and maintained in the chamber 224, and by which pressure maybe released from the chamber 224. For describing the followingoperation, it should be assumed, however, that pressure is beingmaintained in the chamber 224 to maintain the slug 226 in a rightwardposition, to in turn maintain the guide 232 against the snap ring 236.

With the parts as shown in FIG. 3, the spring 200 and the spring 218 arebeing held in a preloaded state. Application of fluid pressure throughbranch conduit 50 applies fluid pressure th the valving spool 72, butsuch fluid pressure is blocked from reaching the clutch 30 which is inan engaged state. Fluid pressure is also applied from the source throughthe branch conduit 52, and into the bore 70 of the valve body 62adjacent the valving spool 106. Pressure is supplied therefrom throughthe conduit 146 to the brake 38 to build up pressure therein, tendingtoward a releasing of the brake 38. Upon pressure build up in the areaof the ports 132, pressure also builds up in the chamber 120 (FIGS. 3and 6) and through the passage 124 to act against the slug 116, movingthe valving spool 106 leftwardly (FIG. 3) until the valving spool 106reaches a balance point wherein sufficient pressure is being supplied tothe brake 38 to release such brake 38. It is to be noted that upon suchsufficient pressure reaching the brake 38 to release such brake, thepriority valve 150 moves leftwardly to an extent to allow pressure intoconduit 244, communicating the bore of such priority valve 150 to supplyoperating fluid pressure to the selector control 22 and transmission 42.Such priority valve 150 is included to preclude the possibility that, asthe clutches in the transmission 42 fill during a transmission shift,the brake pressure might drop to cause the brake 38 to engage. Throughsuch priority valve 150, it is insured that pressure to the transmission42 to fill such transmission clutches is cut off if the pressuresupplied to the brake 38 fails below a certain level. That is, a certainlevel of fluid pressure is supplied to the brake 38 to provide fordisengagement thereof prior to fluid pressure being supplied to theselector control 22 and transmission 42.

As an alternative, the priority valve could be deleted, and a flowrestrictor could be placed in a line to limit back flow of fluid fromthe brake 38, but with such restrictor being positioned so that upon adrop of supply fluid pressure, the pressure supplied to the transmissiondirectly drops therewith, i.e., the restrictor is positioned to restrictflow from the brake, and not from the transmission. In such system, upona drop in supply pressure, the restrictor acts to more slowly releasepressure from the brake than from the transmission.

In order to further actuate the apparatus as thus far described,reference is also made to FIG. 10. Upon initial leftward movement of theplunger 164 by means of actuation of the hand control 188 (FIG. 1),valving spool 72 moves leftwardly against the resilience of the spring82, but with valving spool 106 moving only slightly leftwardly since thespring 242 is chosen to provide sufficient force to maintain fluidpressure to the brake 38, at this point. During such plunger travel, theplunger 192 (FIGS. 3 and 4) moves generally with the plunger 164 (i.e.,spring 200 is not further compressed). Upon sufficient travel of thevalving spool 72, conduit 50 opens to conduit 144, and the conduit 144is blocked off from tank 142, to provide a pressure buildup in theclutch 30 to initlate disengagement thereof. Such application ofpressure occurs at about 3 millimeters travel of the plunger 164 fromits rightward, or rest position. Similar to the valving spool 106,pressure is built up in the chamber 88 (FIGS. 3 and 5) through theradial ports 100, to act on the slug 84 to limit further leftwardmovement of the spool 72, i.e., to achieve a balance point of thevalving spool 72. As illustrated in FIG. 10, the pressure acting on theslug 84 and within the chamber 88 increases the effort necessary to movethe plunger 164 further leftward.

Further movement of the plunger 164 (FIGS. 2 and 3) leftward providesfor increase in fluid pressure supplied to the clutch 30 to furtherdisengage the clutch 30, and further release of fluid pressure from thebrake 38. Corresponding to about seven and one-half millimeters oftravel of the plunger 164, sufficient pressure has been released fromthe brake 38 to provide for initial engagement of the brake 38. At suchpoint, the pressure supplied to the clutch 30 has not risen quitesufficiently to effect full disengagement of the clutch 30. Furthertravel of the plunger 164 (FIGS. 2 and 4), with the plunger 192 stillmoving generally therewith, brings the plunger 192 into contact withshoulder 246 defined by the valve body 62. Such point occurs upon aboutnine and one-half millimeters of travel of the plunger 164 from its restposition, and because of the preload of the spring 200, a relativelysharp increase in effort is required to move the plunger 164 furtherleftward. Such point corresponds to full pressure being applied to theclutch 30 to signal the operator that the clutch 30 is fully disengaged.At this point, pressure supplied to the brake 38 has dropped further,and the brake 38 is in a somewhat more engaged state.

Upon contacting of the plunger 192 with the shoulder 246, the plunger214 (FIGS. 3 and 4) having moved generally with the plunger 164,continues to so move generally with the plunger 164. Providing for suchmovement is the movement of the plunger 164 from a travel ofapproximately nine and one-half millimeters to a travel of approximatelytwenty millimeters by means of the hand control 188 (FIG. 1). Upon theplunger 164 having traveled approximately twenty millimeters leftwardly,a shoulder 248 (FIG. 4) defined by the plunger 214 is brought intocontact with a shoulder 250 defined by the plunger 192, and since thespring 218 is in a preloaded condition, the effort necessary to move theplunger 164 further takes a sharp step upward as shown in FIG. 10. Suchstep is chosen to indicate to the operator that he is approaching abrake mode which is different from the previous one.

Further movement of the plunger 164 compresses both the spring 200 andthe spring 218 (FIG. 4).

During movement of the plunger 164, the piston rod 228 (FIGS. 3 and 4)and cylinder 240 have been extending, with the spring 114 extending,with the valving spool 106 being moved at a rate slower than the plunger164, to apply the brake 38 in a relatively gradual manner. Upon fullextension of the rod 228 and cylinder 240, the head 238 contacts aninwardly extending wall 252 defined by the cylinder 240, so that thespring 242 is taken out of the system, and further movement of theplunger 164 moves the valving spool 106 at the same rate of movement asthe plunger 164. Thus, further movement of the plunger 164, i.e.,occurring at approximately 21 millimeters of travel of the plunger,applies the brake 38 in a relatively more rapid manner. The step inforce, of which the operator is aware, signals that such operator isapproaching the area wherein relatively more rapid brake engagement willoccur upon a given travel of the plunger 164. And, upon full extensionof the piston rod 228 and cylinder 240, the spring 242 is removed fromthe system, so that the operator is aware of a further increase ineffort necessary to move the plunger 164 a given distance.

After full leftward travel of the plunger 164, providing for engagementof the brake 35 and disengagement of the clutch 30, the hand control 188may be released to allow the plunger 164 to move rightwardly under theforce of the resilient springs associated therewith. It has been founddesirable to control the reengagement of the clutch 30, so that a suddenshock need not be absorbed in the drive train of the vehicle due tosudden engagement of such clutch 30. To accomplish this, a damper sleeve254 (FIGS. 3 and 4) is disposed about the plunger 164, to bereciprocable thereon. The sleeve 254 is limited in movement in onedirection relative to the valve body 62 by a snap ring 258 disposed in agroove defined by the valve body 62, with the sleeve 254 defining anannular rib 260 disposed between such shoulder surface 256 and snap ring258. In fact, the full rightward movement of the plunger 164 isdetermined by a radial flange portion 262 (FIG. 3) defined by theplunger 164 contacting the sleeve 254, with the sleeve 254 in turn beinglimited in movement by such shoulder surface 256 of the valve body 62.

Upon initial leftward movement of the plunger 164, fluid is allowed toflow through a port 264 (FIGS. 3 and 4) in the plunger 164 into anannular recess 266 defined by the inner surface of the sleeve 254, andthrough an elongated slot 268 (defined by the plunger 164) into achamber 270 defined by both the plunger 164 and the sleeve 254. Fluid isalso allowed to flow into such chamber 270 as the chamber 270 increasesin size through small ports 272,273 (FIG. 4), sleeve 254 now drawingaway O-ring 274 from shoulder surface 256, such O-ring 274 being fixedto sleeve 254, to allow flow through ports 273. As the plunger 164 movesleftward, increasing the chamber 270 size, the port 264 no longercommunicates with the annular recess 266, so that fluid flowing into thechamber 270 flows through ports 272,273. Upon sufficient leftwardmovement of the plunger 164, fluid is allowed to communicate with thechamber 270 through the slot 268 itself, which has now extended past theleftward end of the sleeve 254.

As stated above, subsequent to full leftward travel of the plunger 164,the controls may be released, and the resilient means associated withthe plunger 164 bias the plunger 164 for movement back to the originalposition thereof. Upon such rightward movement of the plunger 164, itshould be noted that fluid may exit from the chamber 270 through boththe ports 272 and the slot 268 (O-ring 274 now being engaged by shouldersurface 256 to block flow through ports 273). Thus, movement of thevalving spool 72 rightward, determined by movement of the actuator means158, is moved at a certain rate until the slot 268 no longer extendsbeyond the leftward end of the sleeve 254. As the chamber 270 volumefurther decreases, fluid may flow therefrom only through the small ports272, so that movement of the valving spool 72 determined by movement ofthe plunger 164 is subsequently at a slower rate. The slot 268 and ports272 are positioned relative to each other to provide that thesubsequently slower rate corresponds to substantial release of fluidpressure from the clutch 30 providing for engagement of the clutch 30,so that the clutch engagement takes place in a relatively gradualmanner.

As the chamber 270 further decreases in size due to rightward movementof the plunger 164, port 264 is brought into communication with recess266, allowing fluid to flow from such decreasing size chamber 270 notonly through small ports 272, but also through slot 268 and recess 266and port 264. This provides for relatively more rapid or faster movementof the valving spool 72 upon movement of the plunger 164.

It should be noted that with pressure applied against slug 84 (FIGS. 3and 5), the valving spool 72 may be moved leftwardly relatively rapidlyupon rapid movement of the plunger 164, with the poppet 90 lifting offthe seat 94 to allow movement of the slug 84 relatively inwardly of thevalving spool 72. The poppet associated with the valving spool 106(FIGS. 3 and 6) will operate in the same manner if a sudden rightwardmovement of the valving spool 106 is desired, with pressure beingapplied to the slug 116.

As set forth above, the apparatus operates in the abovedescribed mannerwith pressure applied to the chamber 224 (FIGS. 3 and 4) to keep theguide 232 in engagement with the snap ring 236. Release of fluidpressure from such chamber 224 allows the spring 242 and the spring 114to extend somewhat, moving the guide 232 and rod 228 leftward in FIG. 3.The valving spool 106 is thereby moved leftwardly from a positionwherein fluid pressure is supplied to the brake 38 to release the brake38, to a position wherein fluid pressure is released from the brake 38to apply the brake 38. Means are included for selectively applying fluidpressure to and releasing fluid pressure from the chamber 224. Suchmeans are shown in FIGS. 1, 7 and 8.

As shown therein, pressure is supplied from the source through a conduit300 (FIG. 1) to a parking brake valve 302 and therethrough through aconduit 304 to a transmission controlled valve 306 communicating withthe transmission 42 through conduit 308 for providing application of thebrakes of the vehicle during a shift of the transmission 42 from forwardto reverse. Such transmission controlled valve 306 is described inapplication Ser. No. 566,501 entitled "Control System To Apply VehicleBrakes During A Transmission Directional Shift", assigned to theassignee of this invention. It is to be understood, however, that suchtransmission controlled valve 306 may be excluded from the apparatus ifdesired. Fluid pressure is supplied from such transmission controlledvalve 306 to brake valves 310,312 (through conduits 314,316) operativelyassociated with brake pedals 318,320 (FIGS. 1, 2 and 7), one beingassociated with one valve portion 54 and the other being associated withthe other valve portion 58. Each brake valve 310,312 also has conduitmeans 322 associating it with tank 142. Since the operation of bothvalves 310,312 is the same, in combination with a valve portionassociated therewith, only the construction and operation of one will bedescribed in detail.

With the parking brake valve 302 in the position shown in FIG. 8, fluidpressure is supplied from the source through the valve 302 to thetransmission controlled valve 306 and the conduit 314. The conduit 314communicates with a bore 324 defined by a second valve body 326 of thebrake valve 310 (FIG. 7), such bore 324 having a valving spool third oradditional 328 reciprocable therewithin. Also movably disposed withinthe bore 324 is an actuator 330. A helical spring 332 is disposedbetween a rib 334 defined by the valving spool 328 and an end plate 336of the valve body 326, and a helical spring 338 is disposed between theactuator 330 and the valving spool 328. The valve body 326 has pivotallyfixed thereto a shaft 340 on which an arm 342 is secured. The shaft 340also has fixed thereto the brake pedal 318. A lever member 344 issecured to the shaft 340, and has a rod 346 pivotally fixed thereto andextending downwardly therefrom. The rod 346 extends through a tubularmember 348 fixed relative to the valve body 326, and has a nut 350 fixedto the extending end thereof. A resilient spring 352 bears on an endmember 354 fixed to the tubular member 348 and a washer 356 which inturn bears on the nut 350, to urge the rod 346 into a downward position,in turn urging the brake pedal 318 to its upward or second position toin turn urge the valving spool 328 to the leftward position as shown inFIG. 7. In fact, the resilient spring 352 is sufficiently strong to biasthe brake pedal 318 into such second position to normally position thebrake pedal 318 in such second position and the valving spool 328 in theleftward position against the resilience of the spring 332. However, itwill be seen that upon movement of the brake pedal 318 in the oppositedownward direction to a first position thereof, the valving spool 328 ismoved under the resilience of the spring 332 to a rightward position.

In the leftward position of the valving spool 328, the pressure suppliedthrough conduit 314 to the bore 324 passes through a conduit 358communicating the bore 324 and the chamber 224 (FIGS. 3 and 4), so thatfluid pressure is supplied to the chamber 224 so that in turn the guide232 is kept in contact with the snap ring 236. Upon pressing of thebrake pedal 318, the valving spool 328 is allowed to move rightwardlythrough the resilience of the spring 332, to provide communicationbetween the chamber 224 (through the conduit 358) and the valve bodybore 324, and the conduit 322 communicating the valve body bore 324 totank. Thus, pressure is released from the chamber 224 to provide thatthe valving spool 106 is moved leftwardly to dump fluid pressure fromthe brake 30 so that the brake 30 is applied independently of anymovement of the plunger 164 or valving spool 72.

In the operation of the parking brake valve 302, the knob 360 thereof ismoved rightwardly (FIG. 8) to move the spool 303 to cut offcommunication between conduit 300 and conduit 304, and to providecommunication between conduit 304 (communicating with brake valve 310)and conduit 322 communicating with tank. Once fluid pressure is releasedfrom conduit 314 and thereby from valve 310, fluid pressure is in turnreleased from chamber 224 to allow leftward movement of the valvingspool 106 as described above to apply the brake 38.

Shown in FIGS. 11 and 12 is another embodiment of actuator means 400, incombination with first and second valving spools 402, 404 which operatein a manner as described above. In this embodiment, the actuator means400 comprise a lever arm 406 with which is associated a push-pull cable408, the lower end of the lever arm 406 acting on a radial flange 410defined by a plunger 412 movable along the bore 414 defined by the valvebody 416. Plunger 418 is adjacent the plunger 412, and is movablerelative thereto along the bore 414 defined by the valve body 416, theplunger 418 being disposed generally within a bore 420 defined by theplunger 412. A helical spring 422 is included for urging the plungers412,418 relatively apart. Yet another plunger 424 is disposed generallywithin a bore 426 defined by the plunger 418 and inward of the plunger412, and a resilient helical spring 428 interconnects the valving spool402 and the plunger 424. A central passage 430 is provided in theplunger 424. A resilient helical spring 432 interconnects the cap 434and the valving spool 404, with no spring capsule arrangement beingincluded therein. A resilient helical spring 436 urges the valving spool402 toward the plunger 424, and a resilient helical spring 438 urges thevalving spool 404 toward the plunger 412. As shown, the plunger 418defines an inner step 440 which engages an outer step 442 defined by theplunger 424, with the parts shown in the rest position as shown in FIG.11.

The lever arm 406 moves the plunger 412 leftwardly, with the plunger 418being movable generally therewith upon initial movement of the plunger412, in turn moving the valving spools 402,404 substantially asdescribed above. Upon sufficient movement of the plunger 412 leftwardly,the plunger 418 is brought into contact with a shoulder 444 defined bythe valve body 416, whereupon further movement of the plunger 412compresses the resilient spring 422. The resilient spring 422 waspreviously in a preloaded state so that a step in force necessary tomove the spools 402,404 further leftwardly will be noticed by theoperator of the vehicle.

During such compression of the spring 422, relative movement between theplunger 418 and plunger 412 takes place. If such movement takes placerelatively slowly due to relatively slow leftward movement of theplunger 412, fluid will be allowed to exit from the chamber 446 in whichhelical spring 422 is disposed through a small port 448. However, ifsudden leftward movement of the plunger 412 were to take place, i.e.,for example if it is desirable to suddenly apply the brakes of thevehicle, fluid pressure buildup in such chamber 446 will force theplunger 424 leftwardly relative to the plunger 412 to allow fluidpressure to flow through the passage 430. Through such means, it isinsured that the full brake can be applied rapidly if desired.

A damper sleeve 450 is associated with the plunger 412 in a mannersimilar to that previously described, with a spring 452 being utilizedto maintain the damper sleeve 450 in a fully rightward position relativeto the valve body 416. Movement of the plunger 412 leftwardly relativeto the damper sleeve 450 initially allows fluid flow into the chamber454 only through the small ports 456 and the end ports 458 through thechannels 460 provided in the plunger 412. Further leftward movement ofthe plunger 412 relative to the sleeve 450 allows fluid flow into thechamber 454 only through the small ports 456. Even further movement ofthe plunger 412 relative to the sleeve 450 allows fluid flow into theexpanding chamber 454 through lateral passages 462 provided in thesleeve 450. Upon reverse movement of the plunger 412 relative to thesleeve 450, fluid is allowed to exit from the decreasing-size chamber454 through the ports 456 and the lateral passage 462. Upon a certaindegree of relative travel having occurred, the lateral passages 462 areclosed, and fluid is allowed to flow from the decreasing-size chamber454 only through the ports 456. As the plunger 412 approaches its fullrightward movement, fluid flow is again allowed from the decreasing-sizechamber through the channels 460 and the end ports 458, and also throughthe ports 456. During that period when fluid is only allowed to flowthrough the ports 456, it will be understood that the rightward movementof the plunger is relatively slow, as compared to the initial andsubsequent movements relative thereto. Such relatively slow movement ischosen to coincide with the engagement of the clutch, so that a suddenengagement thereof does not take place, but rather a gradual engagementthereof is provided.

In FIGS. 13-15 as shown a system incorporating yet another embodiment ofcontrol valve 500. Such control valve 500 is associated with a pressuresource 502, brakes 504,506, clutches 508,510, and a transmission 512 ina manner similar to the above-described system. Similarly, first fluidcommunication means or conduit 572 provides fluid communication betweenpressure source 502 and control valve 500, and second fluidcommunication means or conduits 574 and 576 provide fluid communicationsbetween control valve 500 and clutches 508 and 510, respectively. Alsosimilarly, third fluid communication means or conduits 578 and 580provide fluid communications between control valve 500 and brakes 504and 506, respectively, and fourth fluid communication means or conduit582 provides fluid communication between control valve 500 and tank 584.However, in this control valve 500 the hand controls 514,516 operatepush-pull cables 518,520 which in turn move bar members (as at 522) inone and the ther directions, and the brake pedals 524,526 operate shafts528,530 which rotate in one and the other directions, each bar and shaftbeing associated with a brake spool 532 and a clutch spool 534 toactuate the clutch and brake of one side of the vehicle in the mannergenerally described above. A priority valve 536 is also included,similar to the priority valve described in the first embodiment.

In this embodiment, the second spool 532 is moved leftwardly (FIG. 15)to apply fluid pressure to the brake 504 to release the brake 504, andrightwardly to release fluid pressure from the brake 504 to apply thebrake 504. The clutch spool 534 is moved rightwardly to release fluidpressure from the clutch 508 to engage the first or clutch 508, andleftwardly to apply fluid pressure to the clutch 508 to disengage theclutch 508. A link 538 is pivotally mounted relative to the valve body540 and has a portion 547 thereof operatively associated with thevalving spool 534 through a rod 542 and an actuator 544, and a resilientspring 546 interconnecting the actuator 544 and the valving spool 534,so that pivotal movement of the link 538 in a first or clockwisedirection moves the valving spool 534 leftwardly, and pivotal movementof the link 538 in a second or counterclockwise direction allows thevalving spool 534 to move rightward under the resilience of spring 548.The opposite end 550 of the link 538 has a roller 552 mounted thereon,positioned to rollably associated with a recess 554 defined by the bar522. The recess 554 of the bar 522 actually defines a ramp surface 556,so that it will be seen that through contacting of the roller 552 withthe bar 522, as the bar 522 is moved in a first or rightward direction,pivoting of the link 538 in its first pivotal direction takes place,with the roller 552 riding up the ramp surface 556 outwardly of the bar522. The ramp surface 556 acts to provide gradual pivoting of the link538 in the first pivotal direction thereof, to provide for gradualdisengagement of the clutch 508. An extended member 558 extends from aplunger 559 which is in turn operatively associated with the valvingspool 532, so that movement of the extended member 558 in one directionmoves the valving spool 532 to a brake releasing position, and movementof the extended member 558 in the other direction moves the valvingspool 532 to a brake applying position. The extended member 558comprises a substantially T-shaped member 560 as shown. The bar 522 ismade up of a body portion 562 and an extending arm portion 564 fixed tothe body portion 562, so that upon sufficient movement of the bar 522 inthe first direction, the extending arm portion 564 contacts one limb 566of the T-shaped member 560. Thus, upon sufficient movement of the bar522 in a first direction, rightwardly as shown in FIG. 15, the clutchspool 534 is moved to a position to disengage the clutch 508, and thebrake spool 532 is moved to a position to engage the brake 504.

Shaft 530, as stated above, is rotatably mounted relative to the valvebody 540, and a lug 568 is fixed to the shaft 530 to be movabletherewith. The shaft 530 is biased so that the lug 568 is in a leftwardposition as shown in FIG. 15, and upon actuation of the brake pedal 524,the shaft 530 rotates to bring the lug 568 into contact with the otherlimb 570 of the T-shaped member 560 to move the valving spool 532 todetermine a braking position. Such actuation is independent of anymovement of the bar 522. It will thus be seen that the brake may beselectively applied even with the clutch engaged. It will be understoodthat the other valve portion of valve 500 includes clutch and brakevalving spools for association with the opposite side clutch 510 andbrake 506 of the vehicle.

We claim:
 1. In a vehicle in which driving force is applied to bothsides thereof, including clutch and brake systems associatedrespectively with both sides thereof and responsive to fluid pressurefrom a source thereof for steering of the vehicle, each clutch and brakesystem associated with a side of the vehicle comprising clutch meansdisengageable to disconnect the driving force applied to that side ofthe vehicle and engageable to connect the driving force to that side ofthe vehicle and brake means actuatable to brake that side of thevehicle, and releasable to release that side of the vehicle, a controlapparatus for each clutch and brake system comprising:a valve comprisinga valve body, and first and second valving spools movably associatedtherewith; first means for providing fluid communication between saidforce and said valve means; second means for providing fluidcommunication between said valve means and said clutch means; thirdmeans for providing fluid communication between said valve means andsaid brake means; fourth means for providing fluid communication fromsaid valve means and through which fluid pressure may be released fromsaid valve means; the first valving spool being movable relative to saidvalve body to first and second positions, the first valving spool in oneof said first and second positions allowing release of fluid pressurefrom said clutch means through said second fluid communication means andsaid fourth fluid communication means, the first valving spool in theother of said first and second positions providing communication offluid pressure from said source through said first fluid communicationmeans, through said second fluid communication means, to the clutchmeans; the second valving spool being movable relative to said valvebody to first and second positions, the second valving spool in one ofsaid first and second positions providing communication of fluidpressure from said source through said first fluid communication means,through said third fluid communication means, to said brake means, thesecond valving spool in the other of said first and second positionsallowing release of fluid pressure from said brake means through saidthird fluid communication means, and said fourth fluid communicationmeans; means for providing movement of said first and second valvingspools, comprising link means pivotally mounted relative to said valvebody and having a portion thereof operatively associated with said firstvalving spool so as to be pivotable in a first direction to move saidfirst valving spool to the second position, and means for providingmovement of said first valving spool to said first position thereof withpivoting of the link means in a second pivotal direction; bar meansoperatively coupled with said link means and movable in a firstdirection to pivot the link means in said first direction; an extendedmember operatively coupled with said second valving spool so as to bemovable in one or the other directions to provide movement of the secondvalving spool to said first and second positions thereof, the bar meansupon movement to pivot said link means in the first direction contactingsaid extended member to move the second valving spool.
 2. The apparatusof claim 1 wherein said extended member comprised a substantiallyT-shaped member, and wherein said bar means comprises a body portion andan extending arm portion fixed to said body portion, positioned tocontact one limb of the T-shaped portion.
 3. The apparatus of claim 2and further comprising means operable independently of said bar means tocontact the other limb of the T-shaped portion to move the secondvalving spool independently of the first valving spool.
 4. The apparatusof claim 3 wherein the bar means defines a recess defining a rampsurface, and further comprising a roller rollably fixed to the linkmeans and positioned to contact said bar means and ride up the rampsurface outwardly of the bar means as said bar means is moved to movethe first valving spool from its first to its second position.
 5. Theapparatus of claim 1 wherein the bar means defines a recess defining aramp surface, and further comprising a roller rollably fixed to the linkmeans and positioned to contact said bar means and ride up the rampsurface outwardly of the bar means as said bar means is moved to movethe first valving spool from its first to its second position.
 6. Theapparatus of claim 1 and further comprising means operable independentlyof said bar means to move the second valving spool independently of thefirst valving spool.
 7. The apparatus of claim 3 wherein said meansoperable independently of said bar means comprise shaft means rotatablymounted relative to said valve body, and lug means fixed to said shaftmeans and positioned to contact the other limb of the T-shaped portionto move the second valving spool independently of the first valvingspool.